Hard rock drill head



o. A. LETTS 2,595,962

HARD ROCK DRILL HEAD 2 SHEETSSHEET l llllllliiiiii May 6, 1952 Filed May 6, 1948 Inventor ORLANDO ARTHUR LETTS d zis lxttorney y 6, 1952 o. A. LETTS 2,595,962-

HARD ROCK DRILL HEAD Filed May 6, 1948- 2 SHEETS-SHEET 2 Inventor ORLANDO ARTHUR LETTS is Attorney ?atented May 6, 1952 UNITED STATES PATENT OFFICE HARD ROCK DRILL HEAD Orlando Arthur Letts, Montreal, Quebec, Canada Application May 6, 1948, Serial No. 25,387

7 Claims.

This invention relates to improvements in a hard rock drill head, appertaining particularly to one having replaceable teeth or nibs of exceptionally hard and durable material.

Among the objects of the present invention are to provide a drill head of simpler, stronger and better design in which the super-hard teeth can be easily and quickly secured; interlocking teeth held in a novel manner and so formed and fitted to the head as to distribute and dissipate impact with the minimum of injury to the teeth and head and without danger of relative accidental displacement of the parts; and a secure and positive yet easily releasable connection between the head and drill rod shank.

A further object of the invention is to provide a new rock drill especially designed for the extra hard rock encountered in the Dre-Cambrian shield that may be manufactured at a reasonable price yet is capable of cutting drill costs from 50 to 80 percent.

To the accomplishment of these and related objects as shall become apparent as the description proceeds, the invention'resides in the construction, combination and arrangement of parts as shall be hereinafter more fully described, illustrated in the accompanying drawings, and pointed out in the claims hereunto appended.

The invention will be best understood and can be more clearly described when reference is had to the drawings forming apart of this disclosure wherein like characters indicate like parts throughout the several views.

In the drawings:

Figure 1 is a sectional elevation of my assembled drill head;

Figure 2 is an elevation of the stripped or skeleton head;

Figure 3 is a top plan and Figure 4 a bottom plan thereof;

Figure 5 is an elevation of the end of the drill steel or shank;

Figure 6 is a section therethrough as taken on line B-fi, looking in the direction indicated by the arrows;

Figures 7, S and 9 are a side elevation, outside end elevation and bottom plan respectively of the instant form of tooth;

Figure 10 is an elevation'of the centre locking sleeve; and

Figures 11 and 12 are elevations of the teeth and shank locking rings respectively.

My improved drill calls for a head I of novel and unique design having a shank or drill rod socket :2 in its base 3 and radial slots 4 in its.

slightly flared outer end 5 preferably in the form of diametrical or diagonal slots intersecting at the heads axis and dividing the same into sectorshaped quarters. The base 6 of the slots 4 slope downwards toward the centre of the head through which runs the usual cleaning fluid axial bore 8. Concentric with this bore where it emerges in the intersecting grooves there is a shallow annular seat 9, of greater diameter than the width of the slots At the inner corners formed by the interseating slots 4 an angular or L-shaped seat I0 is cut, extending down in rectangular form for about a third of the depth of the slots.

A circumferential groove l l is cut in the outer rim of the flaring end 5 extending from a level about th middle of the depth of the slots to about three-quarters of their depth. It is for the accommodating of a spring keeper or locking ring l2. A somewhat similar encircling groove I3 is out in the skirted lower end 3 and likewise accommodates a locking ring l4.

Seating in the shallow seat 9 is an axially positioned hollow post or sleeve l5 that serves in a sense as an anvil, rising three-quarters of the way to the top of the head and includes a pair of well spaced, externally projecting annular flanges It.

The teeth or nibs l1 standing vertically and disposed radially are of a width to fit tightly in the slots i. Both top and. bottom l8 and I9 are sloped or tapered to the outside of the head, the latter at an incline to conform with the slope of the base 6 of the accommodating slot 4. The top It is bevelled equally on each side to provide a central cutting ridge 20 and rises, as seen in Figure l, substantially above the quartered and fluted outer end of the head 5. Furthermore, these teeth ll extend radially beyond the circumference of the slightly flared bit head I, their outer ends 21 below the end of the head then tapering in to meet and conform to the contoiu' of the bit thus allowing a sufficient body in the projecting top and ends of the teeth to withstand considerable wear and still maintain the gauge or size of the drill hole for the life of the teeth. About two-thirds of the way in from its bevelled and sloping top t8, the outer end 2| of each tooth, where it registers with the bit head encircling groove H, is correspondingly notched as at 22 for the reception of the locking ring l2. The inner, centre post engaging ends 23 of the teeth are concaved to conform to the circular form of the sleeve I5 and have a registering pair of spaced transverse notches 24 in which the centre post flanges l6 are accommodated to prevent the relative longitudinal displacement of tooth and post. The imier corners of the teeth where they engage the adjoining teeth on either side are mitered as at 25 and, near the top l8 reaching from about the upper notch 24 to the bottom of the bevel to the cutting ridge, they have lateral wings 26 flush with the miters 25 on contacting faces and of otherwise rectangular form for seating in and conforming to the shape of the confronting portion of the L-shaped seat It] in each case. These wings provide an increased engaging area for joining teeth to receive inwardly directed impact besides holding the teeth against radial separation from the head.

The drill rod shank 21 for releasable reception in the socket 2, that preferably has a slight taper towards its inner end, is formed with three eccentric or cam-like surfaces 28 for locking engagement with corresponding eccentric surfaces 29 on the interior of the socket 2 for jamb lockin engagement on the relative rotation of the parts. Additionally the skirt 3, under the groov I3 has three circumferentially elongated radial slots 30 through into the socket and in the shank 21, in registry with these slots are circula radially disposed bores M to receive separable locking pins or dowels 32 kept in place by the spring locking ring M. It will thus be seen that while the cam locking structure of the shank and bit will provide a tight coupling of the parts, these dowel pins held in plac by the spring ring will eliminate any possible accidental separation of shank and bit.

From the foregoing description taken in connection with the accompanying drawings, it will be manifest that a hard rock drill head is provided that will fulfill all the necessary requirements of such a device, but as many changes could be made in the above description and many apparently widely different embodiments of the invention may be constructed within the scope of the appended claims, without departing from the spirit or scope thereof, it is intended that all matters contained in the said accompanying specification and drawings shall be interpreted as illustrative and not in a limitative or restrictive sense.

Having thus described the invention, what I claim as new and desir to secure by Letters Patent is:

1. A rock drill head having radial slots in the outer end thereof, the inner ends of said slots being widened and the base of said slots sloping downwards toward the centre of said head, replaceable teeth receivable in said slots having lateral wings on their inner ends .fitting in the widened inner ends of said slots and having sloping bottoms corresponding with the slope of the base of said slots and oppositely sloping upper edges; and means releasably securing said teeth in said head against longitudinal displacement.

2. A rock drill having intersecting diagonal slots quartering the outer end thereof, the base of said slots sloping downwards toward the centre of said head, a centre post insertable in said head at the intersection of said slots, radially disposed teeth in said slots with their bottoms sloping to correspond with the bases of said slots and their upper edges oppositely sloping so that they taper outwardly at both top and bottom, said teeth all engaging said centre post at their inner ends interlocking means on said centre post and the inner ends of said teeth, and a drill-encircling teeth-securing means.

3. A rock drill head having intersecting slots quartering the outer end thereof, the base of said slots sloping downwards toward the centre of said head, replaceable teeth receivable in said slots with exposed cutting edges on their exposed tops declining from the centre outwards and their bottoms sloping inwards to correspond with the bases of said slots so that both top and bottom edges of said teeth taper outwardly and the hammering action of the drill tends to force said teeth toward the centre of said head, a removable centre post in said head at the intersection of said slots engaged by and serving as an anvil for the inner ends of said teeth, interlocking means on said centre post and said teeth preventing relative longitudinal displacement, and releasable means securing said teeth in said head.

4. A rock drill head having intersecting diagonal slots quartering the outer end thereof, the base of said slots sloping downwards toward the centre of the head, replaceable teeth receivable in said slots with top exposed cutting edges declining from the centre outwards and their bottoms sloping inwards to correspond with the bases of said slots so that both top and bottom of said teeth taper outwardly and the hammering action of the drill tends to force said teeth toward the centre of said head, a centre post in said head engaged by the inner ends of said teeth, said centre post and teeth having inter-engaging longitudinal anti-displacement connection, and releasable means securing said teeth in said head.

5. A cylindrical rock drill head having intersecting diagonal slots quartering the outer end thereof, the base of said slots sloping downwards toward the centre of said head and a well formed at the base of said slots at their intersection, replaceable teeth receivable in said slots with exposed cutting edges on their exposed tops declining from the centre outwards, spaced vertical ends paralleling the axis of said head and their bottoms sloping inwards to correspond with the bases of said slots so that the hammering action of the drill tends to force said teeth toward the centre of said head, a centre post coaxial in said drill head serving as an anvil for the inner ends of said teeth and formed as an externally flanged sleeve seating in a well in the bottom of the intersecting slots, the inner ends of said teeth having notches to accommodate the centre post flanges, said head having a circumferential groove substantially above the bottom of the diagonal slots therein, said teeth having correspondingly positioned notches across their outer ends and a releasable spring keeper ring in said groove and notches.

6. A rock drill head having intersecting diagonal slots quartering the outer end thereof, the base of said slots sloping downwards towards the centre of said head, and L-shaped seats at the corners formed by said intersecting slots, replaceable teeth receivabl in said slots with exposed cutting edges on their exposed tops declining from the centre outwards and their bottoms sloping inwards to correspond with the bases of said slots so that both top and bottom of said teeth taper outwardly and the hammering action of the drill tends to force said teeth toward the centre of said head and wings extending laterally from opposite sides of said teeth at their inner edges for accommodation in said seats, a centre post in said head engaged by the inner ends of said teeth, interlocking means on said post and the inner ends of said teeth for preventing relative longitudinal displacement and means securing said .teeth in said slotted head and lying flush with the contour of said head.

7. A rock drill head having intersecting slots quartering the outer end thereof, an annular groove in said head above the bottom of said slots, a socket in the base of said head having eccentric, cam-like surfaces, a groove about the socket skirt of said head, slots through from the base of said second groove into said socket, removable teeth in said intersecting slots with notches in their outer ends registering with said first mentioned groove, a central anvil-like sleeve 10 engaged by the inner ends of said teeth and held against longitudinal displacement thereby, a spring ring seating in said first mentioned groove and the notches in the outer ends of said teeth,

confining said dowel pins.

ORLANDO ARTHUR LETTS.

6 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 829,633 Decker Aug. 28, 1906 836,845 Whitcomb Nov. 27, 1906 874,455 Swanton et a1 Dec. 24, 1907 1,718,462 Hardsocg June 25, 1929 2,022,194 Galvin Nov. 26, 1935 2,101,865 McCallurn Dec. 14, 1937 2,110,397 Kangas Mar. 8, 1938 2,252,745 Williams Aug. 19, 1941 2,454,771 Carr NOV. 30, 1943 FOREIGN PATENTS Number Country Date 3,515 Great Britain Feb. 17, 1908 5,778 Great Britain Mar, 14, 1908 799,826 France Apr. 20, 1936 

